finally caved in and got the k-5. i'm sure there will be better reviews out there, but wanted to share my initial impressions.

the good:
faster autofocus even with objects in motion
better exposure. the k20d (in my hands) seemed about 1/3 to 1/2 stop underexposed. k-5 is spot on with no highlight clipping
cleaner high iso pictures (i disabled noise reduction in the menu) 800 to 1600

minor pluses (to me)
hi definition video mode. nice to have it when the camcorder happened to be left at home, but i'd rather have shaved a few hundred dollars of the price that have this
smaller body, but toughness per se is probably even. shooting with my da 40 i do miss that little grip space on the left side of the body of the k20D
faster burst speed
electronic level, but i'd rather get the shot than wait for the little level to tell me that i'm exactly at 0 degrees
full frame viewfinder. what you see is what you get
nice lcd screen

the bad
price. better pictures have and will continue to be taken by a lot of people with less expensive cameras. will it help me get a higher rate of keepers? i don't know but i hope so.
menu got even more cluttered, i actually had to go over the manual

so, the k-5 is a good camera, whether it is worth the expense is an individual decision. for my needs, small children on the move, lots of indoor or poorly lit shots, the faster autofocus and cleaner high iso shots, and the option to do video clinched it for me.